Inasmuch as digital processing is preferred to analog processing, analog signals are converted into digital form by an A/D converter before being used by a digital system. If the analog signal has a small dynamic range, the number of bits required can be economical, but if the dynamic range is large, such as the dynamic range of 2.sup.31 of signals of detectors used with chromatographs, thirty-one bits would be required and the fractional resolution would vary from a value of unity at the low end of the range to a value of one in 2.sup.31 -1 at the high end. In order to reduce the expense and to achieve practical designs, autoranging is used because the dynamic range is larger than practical devices can handle. An autoranging system employs a lesser number of bits to cover successive portions of the dynamic range, but this introduces problems in calibration as well as problems in determining which portion of the range is involved. Another undesirable characteristic is the change in resolution from maximum to minimum value within each portion of the range.